Friction Lining, Process for Its Manufacture and Its Use

Abstract

Aluminum alloys, in particular Al magnesium or Al titanium alloys, are suitable as corrosion protection media in friction linings for automotive brakes and couplings, and serve as a replacement for zinc metal or zinc compounds in such linings.

1 . A method for making a zinc-free friction lining for a motor vehicle braking system, comprising:
 replacing zinc metal, zinc alloys and zinc compounds of a friction lining mixture with an aluminum alloy; and   forming the friction lining for a brake pad that is free of zinc metal, zinc alloys and zinc compounds with the friction lining mixture,   wherein said friction lining has a negative redox potential (E 0  in mV) between that of a friction lining that incorporates a zinc metal and that of a friction lining that incorporates a zinc alloy AlZn 5 .   
     
     
         2 . The method of  claim 1 , wherein the zinc metal and/or zinc alloy is/are replaced with the aluminum alloy in a 1:1 ratio with respect to the respective weight percentage of the friction lining. 
     
     
         3 . The method of  claim 1 , wherein said aluminum alloy comprises aluminum alloyed with one or more of the following metals selected from the group consisting of:
 magnesium (Mg), titanium (Ti), silicon (Si), barium (Ba), strontium (Sr), calcium (Ca), beryllium (Be), zirconium (Zr), chromium (Cr), iron (Fe), tin (Sn), and bismuth (Bi).   
     
     
         4 . The method of  claim 1 , wherein the aluminum alloy is present in an amount from 0.5% by weight to 25% by weight of the friction lining mixture. 
     
     
         5 . The method of  claim 1 , wherein the aluminum alloy is homogeneously dispersed throughout said friction lining mixture in particle form with a particle size in the range of from 100 μm to 700 μm. 
     
     
         6 . The method of  claim 5 , wherein the aluminum alloy particles are spherical. 
     
     
         7 . The method of  claim 1 , wherein the friction lining mixture comprises one or more tin sulfides in an amount from 0.5% by weight to 10% by weight of the friction lining mixture. 
     
     
         8 . The method of  claim 1 , wherein the aluminum alloy is a binary Al—Mg alloy or an Al—Ti alloy. 
     
     
         9 . The method of  claim 1 , wherein the aluminum alloy is a ternary or quaternary alloy containing magnesium (Mg) and/or titanium (Ti) and/or silicon. 
     
     
         10 . The method of  claim 1 , wherein the aluminum alloy is AlTi 10  or AlMg 50 . 
     
     
         11 . The method of  claim 1 , wherein the corrosion resistance (ohm-cm) of the friction lining is between that of a friction lining that incorporates a zinc metal and that of a friction lining that incorporates a zinc alloy AlZn 5 . 
     
     
         12 . The method of  claim 1 , wherein the metal brake component comprises a friction partner contacting the brake pad friction lining of a motor vehicle upon brake activation. 
     
     
         13 . The method of  claim 12 , wherein the friction partner comprises iron and/or steel.